Sample fluid stream probe

ABSTRACT

A sample fluid stream in a probe apparatus may be redirected in a redirection area, and a flowing gas sheet may be directed into the redirection area. Additionally, a conduit downstream of a probe nozzle may define a reverse taper (where the conduit is wider downstream), a lip for collecting droplets that have collected on conduit walls, and/or re-entraining gas directed at collected droplets. Focusing gas may focus the sample fluid stream away from the walls of the conduit. Such focusing gas may be at different temperatures for different sections of the conduit. For example, the focusing gas may be a lower temperature near the probe inlet, and may be at a higher temperature to act as drying gas farther downstream.

BACKGROUND

Probes can be used to collect sample fluid streams from main fluidstreams. For example, probes can be used to collect sample fluid streamsfrom stack emissions, such as wet stack emissions. Wet stacks are stackscontaining main flows of emissions that are saturated with water vaporand have liquid water droplets that can vary from micro droplets typicalof fogs (micrometers in diameter) to macro droplets typical of rain(millimeters in diameter). These droplets can contain a large fractionof particulate matter (PM) and metals associated with health effects. Itcan be difficult to collect a representative sample of these dropletsfor analysis on a continuous basis. Currently, continuous emissionmonitor systems (CEMS) use large diameter probes to reduce deviationsfrom isokinetic sampling, avoid heating sampling probes to minimizedried salt plugs, use steam and compressed air “blow back” to preventprobe build up and plugging, or other similar techniques to allowcontinuous operations.

SUMMARY

Current probes can be ineffective in transporting a representative totalstack aerosol sample to a CEMS. The description herein is directed totools and techniques for probe apparatuses for collecting andtransporting sample fluid streams. For example, a sample fluid streammay be redirected in a redirection area, and a flowing gas sheet may bedirected into the redirection area. Such a gas sheet may provide one ormore of various benefits, such as redirecting the flow while reducingimpact of the flow with conduit walls, mixing the flow to promotedrying, breaking up large droplets in the flow to promote drying, etc.Additionally, a conduit downstream of a probe nozzle may define areverse taper (where the conduit is wider downstream), a lip forcollecting droplets that have collected on conduit walls, and/orre-entraining gas directed at collected droplets. Such features can aidin decreasing impaction of droplets on the conduit walls and/orre-entraining collected droplets into the sample fluid stream. Asanother example, focusing gas may focus the sample fluid stream awayfrom the walls of the conduit. Such focusing gas may be at differenttemperatures for different sections of the conduit. For example, thefocusing gas may be a lower temperature near the probe inlet (which maydecrease overheating of the probe nozzle, which could cause increasedevaporation of droplets on the nozzle), and may be at a highertemperature to act as drying gas farther downstream. Such tools andtechniques and/or others discussed below may be used alone or incombination.

This Summary is provided to introduce a selection of concepts in asimplified form. The concepts are further described below in theDetailed Description. This Summary is not intended to identify keyfeatures or essential features of the claimed subject matter, nor is itintended to be used to limit the scope of the claimed subject matter.Similarly, the invention is not limited to implementations that addressthe particular techniques, tools, environments, disadvantages, oradvantages discussed in the Background, the Detailed Description, or theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of a probe apparatus and taken alongline 1-1 in FIG. 2, with a materials monitoring apparatus illustratedschematically.

FIG. 2 is a top sectional of the probe apparatus of FIG. 1 taken alongline 2-2 in FIG. 1, with the materials monitoring apparatus againillustrated schematically.

FIG. 3 is a flowchart illustrating a probe technique.

The description and drawings may refer to the same or similar featuresin different drawings with the same reference numbers.

DETAILED DESCRIPTION

The probe features discussed herein include many new features that maybe used alone or in combination. For example, the probe apparatus canuse high velocity gas to redirect the flow of stack gas, particles andliquid droplets from the original direction of the stack gas to adirection towards the containment walls where the aerosol can be sampledor analyzed. For example, the high velocity gas can be in the form of agas sheet, which can have a width that is at least ten times, at leastfifty times, at least one-hundred times, at least five-hundred times, orat least one-thousand times a thickness of the gas sheet at an outlet ofa gas knife. Other features can relate to reducing impaction of aerosolcomponents in the sample fluid stream on conduit walls, encouragingre-entrainment of liquid deposited on walls of the inlet nozzle, etc.The various aspects of such features will now be discussed withreference to FIGS. 1-2.

Referring to FIG. 1, a probe apparatus (100) is illustrated. The probeapparatus (100) can include a nozzle area (102), a redirection area(104) downstream of the nozzle area (102), and a transport area (106)downstream of the redirection area (104). For example, the nozzle area(102) may be oriented vertically, with the redirection area (104)turning ninety degrees, and the transport area (106) extendinghorizontally from the redirection area (104). The nozzle area (102) caninclude a shroud (110), which can be mounted on a nozzle (120). Theshroud (110) can be a tube that is connected to the nozzle (120) withcircumferentially spaced beams (not shown) extending between the nozzle(120) and the shroud (110) to mount the shroud on the nozzle.

The nozzle (120) can have a nozzle inlet (122) defined by a leading edgeof the nozzle (120). The nozzle inlet (122) can be centrally locatedwithin the shroud (110). The nozzle inlet (122) can have a diameter thatis substantially smaller than an inner diameter of an entrance to theshroud (110) (e.g., from 0.1 to 0.4 times the diameter of the shroud(110)). For example, the nozzle inlet may have a diameter of aboutthree-fourths of an inch and the shroud may have an inner diameter ofabout three inches. The nozzle can have an outer surface (124) that canslope outward downstream of the inlet (122). An inner surface (126) ofthe nozzle (120) can extend downstream from the nozzle inlet (122). Theinner surface (126) can have a constant diameter for some length (e.g.,for between 1/16 inch to ¼ inch, or ⅛ inch), and can end in a lip (128).From the lip (128), the inner surface (126) can form a reverse taper(130). The reverse taper (130) can extend outward at any of variousdifferent angles, such as an angle less than ninety degrees and/or anangle greater than ninety degrees.

A main conduit (140) can extend back from the nozzle inlet (122),defining a stream area (142) where the sample fluid stream is to flow,as will be discussed more below. The main conduit (140) can include thenozzle (120) and the other conduit components discussed below (e.g., theouter non-porous and inner porous conduit components).

A downstream portion of the nozzle (120) can fit over at least a portionof a first outer non-porous conduit component (150) or can otherwise besecured to the non-porous conduit component (150). The first outernon-porous conduit component (150) can surround a first inner porousconduit component (152) to form a first annular gas chamber (154)between the components (150). A focusing gas source (156) can beconnected in fluid communication with the first gas chamber (154). Thefirst outer non-porous conduit component (150) can be sealed to thefirst inner porous conduit component (152). This seal may not be anentirely gas-tight seal, but it can be sealed sufficiently to forcefocusing gas to pass through the first inner porous conduit component(152). The focusing gas source (156) can provide focusing gas that is ata temperature at or below the temperature of the main fluid streamentering the nozzle (120).

Downstream of the nozzle area (102), the stream area (142) can continueand the main conduit (140) can include a second outer non-porous conduitcomponent (160) surrounding a second inner porous conduit component(162) to form a second annular gas chamber (164) between the secondouter non-porous conduit component (160) and the second inner porousconduit component (162). A drying gas source (170) can be connected influid communication with the second gas chamber (164). The second outernon-porous conduit component (160) can be sealed to the first innerporous conduit component (162). This seal may not be an entirelygas-tight seal, but it can be sealed sufficiently to force focusing gasto pass through the first inner porous conduit component (162). Thefocusing gas source (156) can provide focusing gas that is also heatedto act as drying gas. Accordingly, the drying gas can be at atemperature that is above the temperature of the main fluid streamentering the nozzle (120). The second gas chamber (164) can extend alongthe redirection area (104) and along the transport area (106), providingdrying gas through the second inner porous conduit component (162). Thesecond gas chamber (164) may be interrupted by a joint in the mainconduit (140), so that there is also a third gas chamber (166) that canalso supply drying gas. There may also be additional gas chambers tosupply drying gas and/or unheated focusing gas downstream of the thirdgas chamber (166), leading to a materials monitoring apparatus (180)shown schematically in FIGS. 1 and 2. The materials monitoring apparatus(180) may be any of various types that are able to test the natureand/or quantity of particles in the sample stream flowing through theprobe apparatus (100). For example, the monitoring apparatus (180) maybe an X-ray fluorescence testing apparatus.

Additionally, the probe apparatus (100) can include a gas knife (200)that can be connected to a pressurized gas source (210). The gas knife(200) can define a gap that acts as an outlet (220) through which thepressurized gas can be forced to form a high velocity sheet of flowinggas. The outlet (220) may be curved so that the gas sheet is alsocurved. For example, the outlet (220) can form a concave curve from theperspective of the nozzle (120). Accordingly, the curve of the outlet(220) may match the curve of the conduit (140) distal from the nozzle(120) in FIGS. 1-2. The curve may have radius of curvature that is thesame as a radius of the main conduit (140) in the redirection area(104), and the curve may extend through a radial arc of from forty-fiveto one-hundred and eighty degrees, such as from ninety degrees toone-hundred and twenty degrees. The outlet (220) can have a width thatis greater than a diameter of the sample stream flowing into theredirection area (104), and the outlet (220) can have a thickness thatis less than the width. For example, the outlet (220) can have can havea width that is at least ten times, at least fifty times, at leastone-hundred times, at least five-hundred times, or at least one-thousandtimes a thickness of the outlet (220). For example, outlet (220) may beone and one-half inches wide, and one one-thousandth of an inch thick(from top to bottom). The outlet (220) of the gas knife (200) can bedirected into the redirection area (104). The outlet (220) can bepointed in a different direction from the direction of the flow into thenozzle inlet (122) and into the redirection area (104). For example, theoutlet (220) can be pointed in the same direction as the direction ofthe main conduit (140) downstream of the redirection area (104). If theconduit makes a ninety-degree turn so that the main conduit (140)downstream of the redirection area (104) is at a right angle to thenozzle (120), the outlet (220) of the gas knife (200) may also bedirected at that same right angle.

Various different materials and/or manufacturing methods may be used inthe components of the probe apparatus (100). For example, the componentsmay be made of corrosive-resistant metals such as stainless steel,titanium, or aluminum. Additionally, lightweight metals such as aluminummay be coated with corrosive-resistant coatings. The inner porousconduit components (152 and 162) may be sintered material such assintered stainless steel.

Operation of the probe apparatus (100) will now be discussed withreference to a flowchart illustrated in FIG. 3, and still with referenceto FIGS. 1-2. A sample fluid stream (230) from a main fluid stream (232)can be passed (305) through the shroud (110) and then received (310)through the nozzle (120) of the probe apparatus (100). The shroud (110)can slow the velocity of the fluid stream that passes through the shroud(110). This can create non-isokinetic flow around the edges of theshroud (110), which may cause a disproportionate number of particularsized particles to enter the shroud (e.g., disproportionately more largeparticles such as droplets). However, the flow around the edge of theshroud (110) can pass by the nozzle (120) without entering the nozzleinlet (122). The sample fluid stream (230) that enters the nozzle inlet(122) can be from the center of the shroud (110), where thenon-isokinetic effects of the shroud can be reduced or non-existent.Additionally, the slowed velocity within the shroud (110) can reduce thenon-isokinetic effects of the nozzle (120) on the sample fluid stream(230) entering the nozzle inlet (122). Additionally, the slowed velocitycan reduce the rate of capture of the sample fluid stream (230), so thatthere can be less flow to be transported and analyzed.

The sample fluid stream (230) can travel into the nozzle (120) in afirst direction. Some droplets (240) from the main fluid stream (232)that are not in the sample fluid stream (230) may collect on the outersurface (124) of the nozzle (120). Other droplets (242) in the samplefluid stream (230) may impact and collect on the inner surface (126) ofthe nozzle (120). Such droplets (242) can be forced farther into thenozzle (120) by the flow of the sample fluid stream (230). Thesedroplets (242) can be re-entrained (315) in the sample fluid stream(230). For example, the droplets (242) may collect on the lip (128) thatis upstream of at least a portion of the reverse taper (130). Are-entraining gas flow (250) (e.g., part of a flow of focusing gas (252)from the first gas chamber (154)) can be directed along a flow path tothe droplets (242), such as by flowing along the lip (128) and carryingthe droplets (242) back into the sample fluid stream (230).

The focusing gas (252) passing through the first inner porous conduitcomponent (152) can also be directed into the sample fluid stream (230)from multiple different sides (e.g., from all around the sample fluidstream (230) so that the focusing gas (252) surrounds the sample fluidstream (230)) to focus (320) the sample fluid stream into a central areaaway from the surrounding walls of the first inner porous conduitcomponent (152). This focusing (320) can reduce impaction of dropletsand/or dry particles from the sample fluid stream (230) from impactingwalls of the main conduit (140). Additionally, the reverse taper (130)brings the walls of the main conduit (140) out and away from the samplefluid stream (230), which can also reduce impaction of droplets and/ordry particles from the sample fluid stream (230) on walls of the mainconduit (140).

The sample fluid stream (230) can be redirected (325) in the redirectionarea (104) from the first sample fluid stream direction to a secondsample fluid stream direction. A flowing gas sheet (260) can be directed(330) into the sample fluid stream (230) in the redirection area (104),such as through the gas knife (200). The gas sheet (260) can betraveling in a sheet direction that is different from the first samplefluid stream direction. The gas sheet (260) can redirect at least aportion of the sample fluid stream (230) in the redirection area (104).The gas sheet (260) may also break liquid droplets in the sample fluidstream (230), which can promote drying of such droplets. Additionally,the gas sheet (260) can mix a central portion of the sample fluid stream(230) (which can be cooler and wetter than the rest of the sample fluidstream (230)) with other portions of the sample fluid stream (230). Thismay also promote drying of the overall sample fluid stream (230).

The gas sheet (260) can be wider than the sample fluid stream (230).Also, the gas sheet (260) may be curved and have a high velocity. Forexample, a velocity of the gas sheet (260) may be greater than avelocity of the sample fluid stream (230). For example, the main fluidstream (232) may be flowing with a velocity of about twenty to aboutsixty miles per hour, and this velocity may be cut in half in the shroud(110) before the sample fluid stream (230) enters the nozzle inlet(122). The gas sheet (260) may have a velocity that is from fifty totwo-hundred miles per hour, such as from one-hundred mile per hour toone-hundred and fifty miles per hour. The source of gas for the gassheet (260) can be heated so that the gas sheet may be at an elevatedtemperature, such as a temperature above two-hundred and twelve degreesFahrenheit, such as 250 degrees Fahrenheit.

The sample fluid stream can be transported (335) from the redirectionarea (104), such as to the materials monitoring apparatus (180). Asnoted above, the sample fluid stream (230) can be focused, such as usingfocusing gas (252). The focusing gas (252) in a first section (e.g., thenozzle area (102)) can be a lower temperature than focusing gas in asecond section (e.g., the redirection area (104) and/or the transportarea (106)) downstream of the first section. For example, the focusinggas in the second section can be drying gas (270), which can be suppliedthrough the second gas chamber (164) and possibly through subsequent gaschambers (e.g., the third gas chamber (166)). This drying gas (270) canfocus the sample fluid stream (230) in the redirection area (104) and/orthe transport area (106). The drying gas (270) may be heated to anelevated temperature similar to the temperature of the gas sheet (260).Such high temperatures can heat the sample fluid stream (230) andpromote drying of droplets in the sample fluid stream (230). The gasesdiscussed above may be air and/or one or more other gases.

The subject matter defined in the appended claims is not necessarilylimited to the benefits described herein. A particular implementation ofthe invention may provide all, some, or none of the benefits describedherein. Although operations for the various techniques are describedherein in a particular, sequential order for the sake of presentation,it should be understood that this manner of description encompassesrearrangements in the order of operations, unless a particular orderingis required. For example, operations described sequentially may in somecases be rearranged or performed concurrently. Techniques describedherein with reference to flowcharts may be used with one or more of thesystems described herein and/or with one or more other systems.Moreover, for the sake of simplicity, flowcharts may not show thevarious ways in which particular techniques can be used in conjunctionwith other techniques.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

I claim:
 1. A method comprising: receiving a sample fluid stream from a main fluid stream through a nozzle of a probe apparatus located at least partially in the main fluid stream, the sample fluid stream traveling into the nozzle in a first fluid stream direction; redirecting the sample fluid stream from the first fluid stream direction to a second fluid stream direction in a redirection area; and directing a flowing gas sheet into the sample fluid stream in the redirection area, the gas sheet traveling in a sheet direction that is different from the first direction; and focusing the sample fluid stream by directing focusing gas at the sample fluid stream from multiple different sides of the sample fluid stream.
 2. The method of claim 1, wherein the gas sheet redirects at least a portion of the sample fluid stream in the redirection area.
 3. The method of claim 1, wherein the gas sheet breaks liquid droplets in the sample fluid stream.
 4. The method of claim 1, wherein the gas sheet mixes a central portion of the sample fluid stream with one or more other portions of the sample fluid stream.
 5. The method of claim 4, wherein the central portion of the sample fluid stream is wetter than the one or more other portions of the sample fluid stream as the sample fluid stream enters the redirection area.
 6. The method of claim 5, wherein the central portion of the sample fluid stream is cooler than the one or more other portions of the sample fluid stream as the sample fluid stream enters the redirection area.
 7. The method of claim 1, wherein the gas sheet is wider than the sample fluid stream.
 8. The method of claim 1, wherein the gas sheet is curved.
 9. The method of claim 1, wherein a velocity of the gas sheet is greater than a velocity of the sample fluid stream.
 10. The method of claim 1, further comprising re-entraining droplets from the sample fluid stream that impact an inner surface of the nozzle back into the sample fluid stream.
 11. The method of claim 10, wherein re-entraining comprises directing a re-entraining gas flow at the droplets.
 12. The method of claim 11, wherein the re-entraining gas flow passes along an edge that collects the droplets.
 13. The method of claim 1, wherein a width of the gas sheet is at least ten times a thickness of the gas sheet as the gas sheet enters the redirection area.
 14. The method of claim 13, wherein the width of the gas sheet is at least fifty times the thickness of the gas sheet as the gas sheet enters the redirection area.
 15. The method of claim 1, wherein the focusing gas surrounds the sample fluid stream.
 16. The method of claim 1, wherein the focusing gas in a first section is a lower temperature than the focusing gas in a second section downstream of the first section.
 17. The method of claim 1, further comprising passing a body of fluid through at least a portion of a shroud positioned within the main fluid stream such that a first portion of the main fluid stream passes into the shroud to become the body of fluid while a second portion of the main fluid stream passes around the shroud, wherein receiving the sample fluid stream through the nozzle of the probe apparatus comprises receiving the sample fluid stream from the body of fluid after the body of fluid has passed through the at least a portion of the shroud.
 18. A probe apparatus comprising: a nozzle inlet portion configured to receive a sample fluid stream of a main fluid stream; a conduit in fluid communication with the nozzle inlet portion, the conduit comprising a redirection area downstream of the nozzle inlet portion, the redirection area comprising a turn in the conduit, the conduit being a main conduit that comprises a first porous conduit component surrounded by and sealed to a first non-porous conduit component to define a first gas chamber between the first porous conduit component and the first non-porous conduit component and a stream flow area within the first porous conduit component; a first pressurized gas source in communication with the first chamber; and an outlet pointed into the redirection area, the apparatus being configured so that pressurized gas passing through the outlet forms a gas sheet that meets the sample fluid stream in the redirection area, with the gas sheet and the sample fluid stream traveling in different directions relative to each other until the gas sheet and the sample fluid stream meet in the redirection area.
 19. The apparatus of claim 18, wherein the outlet comprises a curved gas sheet outlet.
 20. The apparatus of claim 18, wherein a reverse taper portion is between the nozzle inlet portion and the redirection area, and the apparatus further comprises a flow path configured to direct re-entraining gas at an edge upstream of the reverse taper portion.
 21. The apparatus of claim 18, wherein: the main conduit further comprises a second porous conduit component surrounded by and sealed to a second non-porous conduit component to define a second chamber between the second porous conduit component and the second non-porous conduit component and the stream flow area within the second porous conduit component; and the apparatus further comprises a second pressurized gas source in communication with the second chamber.
 22. The apparatus of claim 21, wherein the first gas source is a source of gas at a first temperature, and the second gas source is a source of gas at a second temperature that is higher than the first temperature.
 23. The apparatus of claim 18, further comprising a shroud with a leading edge upstream of the nozzle inlet portion, the shroud having an entrance that is larger than the nozzle inlet portion.
 24. A probe apparatus comprising: a nozzle inlet portion configured to receive a sample fluid stream of a main fluid stream; and a conduit in fluid communication with the nozzle inlet portion, a reverse taper portion being downstream of the nozzle inlet portion, the conduit comprising a porous conduit component surrounded by and sealed to a non-porous conduit component to define a gas chamber between the porous conduit component and the non-porous conduit component and to define a stream area within the porous conduit component, the porous conduit component and the non-porous conduit component being downstream of the reverse taper portion.
 25. The apparatus of claim 24, further comprising a source of re-entraining gas directed at droplets collected on the nozzle upstream of at least a portion of the reverse taper portion.
 26. The apparatus of claim 25, wherein the re-entraining gas is directed at an edge upstream of at least a portion of the reverse taper portion.
 27. The apparatus of claim 24, wherein the conduit comprises a redirection area downstream of the reverse taper portion, the redirection area comprising a turn in the conduit.
 28. The apparatus of claim 27, further comprising an outlet pointed into the redirection area, the apparatus being configured so that pressurized gas passing through the outlet forms a gas sheet that meets the sample fluid stream in the redirection area.
 29. The apparatus of claim 28, wherein the outlet comprises a curved gas sheet outlet.
 30. The apparatus of claim 24, further comprising a pressurized gas source in communication with the gas chamber.
 31. The apparatus of claim 30, wherein the chamber is a first gas chamber, the gas source is a first gas source, the porous conduit component is a first porous conduit component, the non-porous conduit component is a first non-porous conduit component, the stream area is a first stream area, and the conduit further comprises a second porous conduit component surrounded by and sealed to a second non-porous conduit component to define a second gas chamber that is downstream of the first gas chamber and to define a second stream area within the second porous conduit component, and wherein the apparatus further comprises a second pressurized gas source in communication with the second gas chamber.
 32. The apparatus of claim 31, wherein the first gas source is a gas source of gas at a first temperature, and the second gas source is a source of gas at a second temperature that is higher than the first temperature.
 33. The apparatus of claim 24, further comprising a shroud with a leading edge upstream of the nozzle inlet portion, the shroud having an entrance that is larger than the nozzle inlet portion. 